/*
 * Copyright (C) 2012 The Libphonenumber Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.i18n.phonenumbers;

import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.google.i18n.phonenumbers.Phonemetadata.PhoneMetadata;
import com.google.i18n.phonenumbers.Phonemetadata.PhoneMetadataCollection;

/**
 * Class encapsulating loading of PhoneNumber Metadata information. Currently this is used only for
 * additional data files such as PhoneNumberAlternateFormats, but in the future it is envisaged it
 * would handle the main metadata file (PhoneNumberMetadata.xml) as well.
 */
class MetadataManager {
	private static final String ALTERNATE_FORMATS_FILE_PREFIX =
			"/com/google/i18n/phonenumbers/data/PhoneNumberAlternateFormatsProto";
	private static final String SHORT_NUMBER_METADATA_FILE_PREFIX =
			"/com/google/i18n/phonenumbers/data/ShortNumberMetadataProto";

	private static final Logger LOGGER = Logger.getLogger(MetadataManager.class.getName());

	private static final Map<Integer, PhoneMetadata> callingCodeToAlternateFormatsMap =
			Collections.synchronizedMap(new HashMap<Integer, PhoneMetadata>());
	private static final Map<String, PhoneMetadata> regionCodeToShortNumberMetadataMap =
			Collections.synchronizedMap(new HashMap<String, PhoneMetadata>());

	// A set of which country calling codes there are alternate format data for. If the set has an
	// entry for a code, then there should be data for that code linked into the resources.
	private static final Set<Integer> countryCodeSet =
			AlternateFormatsCountryCodeSet.getCountryCodeSet();

	// A set of which region codes there are short number data for. If the set has an entry for a
	// code, then there should be data for that code linked into the resources.
	private static final Set<String> regionCodeSet = ShortNumbersRegionCodeSet.getRegionCodeSet();

	private MetadataManager() {
	}

	private static void close(InputStream in) {
		if (in != null) {
			try {
				in.close();
			} catch (IOException e) {
				LOGGER.log(Level.WARNING, e.toString());
			}
		}
	}

	private static void loadAlternateFormatsMetadataFromFile(int countryCallingCode) {
		InputStream source = PhoneNumberMatcher.class.getResourceAsStream(
				ALTERNATE_FORMATS_FILE_PREFIX + "_" + countryCallingCode);
		ObjectInputStream in = null;
		try {
			in = new ObjectInputStream(source);
			PhoneMetadataCollection alternateFormats = new PhoneMetadataCollection();
			alternateFormats.readExternal(in);
			for (PhoneMetadata metadata : alternateFormats.getMetadataList()) {
				callingCodeToAlternateFormatsMap.put(metadata.getCountryCode(), metadata);
			}
		} catch (IOException e) {
			LOGGER.log(Level.WARNING, e.toString());
		} finally {
			close(in);
		}
	}

	static PhoneMetadata getAlternateFormatsForCountry(int countryCallingCode) {
		if (!countryCodeSet.contains(countryCallingCode)) {
			return null;
		}
		synchronized (callingCodeToAlternateFormatsMap) {
			if (!callingCodeToAlternateFormatsMap.containsKey(countryCallingCode)) {
				loadAlternateFormatsMetadataFromFile(countryCallingCode);
			}
		}
		return callingCodeToAlternateFormatsMap.get(countryCallingCode);
	}

	private static void loadShortNumberMetadataFromFile(String regionCode) {
		InputStream source = PhoneNumberMatcher.class.getResourceAsStream(
				SHORT_NUMBER_METADATA_FILE_PREFIX + "_" + regionCode);
		ObjectInputStream in = null;
		try {
			in = new ObjectInputStream(source);
			PhoneMetadataCollection shortNumberMetadata = new PhoneMetadataCollection();
			shortNumberMetadata.readExternal(in);
			for (PhoneMetadata metadata : shortNumberMetadata.getMetadataList()) {
				regionCodeToShortNumberMetadataMap.put(regionCode, metadata);
			}
		} catch (IOException e) {
			LOGGER.log(Level.WARNING, e.toString());
		} finally {
			close(in);
		}
	}

	// @VisibleForTesting
	static Set<String> getShortNumberMetadataSupportedRegions() {
		return regionCodeSet;
	}

	static PhoneMetadata getShortNumberMetadataForRegion(String regionCode) {
		if (!regionCodeSet.contains(regionCode)) {
			return null;
		}
		synchronized (regionCodeToShortNumberMetadataMap) {
			if (!regionCodeToShortNumberMetadataMap.containsKey(regionCode)) {
				loadShortNumberMetadataFromFile(regionCode);
			}
		}
		return regionCodeToShortNumberMetadataMap.get(regionCode);
	}
}
